The K2-24 planetary system revisited by CHEOPS

Astronomy and Astrophysics, vol. 690, pp. A349

Abstract

The planetary system K2-24 is composed of two transiting low-density Neptunians locked in an almost perfect 2:1 resonance and showing large transit time variations (TTVs), and it is an excellent laboratory to search for signatures of planetary migration. Previous studies performed with K2, Spitzer, and RV data tentatively claimed a significant non-zero eccentricity for one or both planets, possibly high enough to challenge the scenario of pure disk migration through resonant capture. With 13 new CHEOPS light curves (seven of planet b, six of planet c), we carried out a global photometric and dynamical re-analysis by including all the available literature data as well. We obtained the most accurate set of planetary parameters to date for the K2-24 system, including radii and masses at 1% and 5% precision (now essentially limited by the uncertainty on stellar parameters) and non-zero eccentricities eb = 0.0498−0.0018+0.0011, ec = 0.0282−0.0007+0.0003 detected at very high significance for both planets. Such relatively large values imply the need for an additional physical mechanism of eccentricity excitation during or after the migration stage. Also, while the accuracy of the previous TTV model had drifted by up to 0.5 days at the current time, we constrained the orbital solution firmly enough to predict the forthcoming transits for the next ~15 years, thus enabling efficient follow-up with top-level facilities such as JWST or ESPRESSO.

Authors 84

1. V. Nascimbeni

   Osservatorio Astronomico di Padova

   Affiliation as printed

   INAF, Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy

2. L. Borsato

   Osservatorio Astronomico di Padova

   Affiliation as printed

   INAF, Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy

3. P. Leonardi

   University of Padua · University of Trento · Osservatorio Astronomico di Padova

   Affiliation as printed

   Dipartimento di Fisica e Astronomia, Università degli Studi di Padova, Vicolo dell’Osservatorio 3, 35122 Padova, Italy

   Dipartimento di Fisica, Università di Trento, Via Sommarive 14, 38123 Povo (TN), Italy

   INAF, Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy

4. S. G. Sousa

   Universidade do Porto · Institute of Astrophysics and Space Sciences · Centro de Astrofísica da Universidade do Porto

   Affiliation as printed

   Instituto de Astrofisica e Ciencias do Espaco, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal

5. Thomas G Wilson

   University of Warwick

   Affiliation as printed

   Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK

6. A. Fortier

   University of Bern · Center for Space and Habitability

   Affiliation as printed

   Center for Space and Habitability, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

   Weltraumforschung und Planetologie, Physikalisches Institut, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

7. A. Heitzmann

   University of Geneva

   Affiliation as printed

   Observatoire astronomique de l’Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

8. G. Mantovan

   University of Padua · Osservatorio Astronomico di Padova

   Affiliation as printed

   Dipartimento di Fisica e Astronomia, Università degli Studi di Padova, Vicolo dell’Osservatorio 3, 35122 Padova, Italy

   INAF, Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy

9. R. Luque

   University of Chicago

   Affiliation as printed

   Department of Astronomy & Astrophysics, University of Chicago, Chicago, IL 60637, USA

10. T. Zingales

    University of Padua · Osservatorio Astronomico di Padova

    Affiliation as printed

    Dipartimento di Fisica e Astronomia, Università degli Studi di Padova, Vicolo dell’Osservatorio 3, 35122 Padova, Italy

    INAF, Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy

11. G. Piotto

    University of Padua · Osservatorio Astronomico di Padova

    Affiliation as printed

    Dipartimento di Fisica e Astronomia, Università degli Studi di Padova, Vicolo dell’Osservatorio 3, 35122 Padova, Italy

    INAF, Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy

12. Yann Alibert

    University of Bern · Center for Space and Habitability

    Affiliation as printed

    Center for Space and Habitability, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

    Weltraumforschung und Planetologie, Physikalisches Institut, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

13. R. Alonso

    Universidad de La Laguna · Instituto de Astrofísica de Canarias

    Affiliation as printed

    Departamento de Astrofísica, Universidad de La Laguna, Astrofísico Francisco Sanchez s/n, 38206 La Laguna, Tenerife, Spain

    Instituto de Astrofísica de Canarias, Vía Láctea s/n, 38200 La Laguna, Tenerife, Spain

14. T. Bárczy
    Affiliation as printed

    Admatis, 5, Kandó Kálmán Street, 3534 Miskolc, Hungary

15. D. Barrado

    Centro de Astrobiología

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    Depto. de Astrofísica, Centro de Astrobiología (CSIC-INTA), ESAC campus, 28692 Villanueva de la Cañada (Madrid), Spain

16. S. C. C. Barros

    Universidade do Porto · Institute of Astrophysics and Space Sciences · Centro de Astrofísica da Universidade do Porto

    Affiliation as printed

    Departamento de Fisica e Astronomia, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal

    Instituto de Astrofisica e Ciencias do Espaco, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal

17. W. Baumjohann

    Austrian Academy of Sciences · Space Research Institute

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    Space Research Institute, Austrian Academy of Sciences, Schmiedl-strasse 6, 8042 Graz, Austria

18. T. Beck

    University of Bern

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    Weltraumforschung und Planetologie, Physikalisches Institut, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

19. W. Benz

    University of Bern · Center for Space and Habitability

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    Center for Space and Habitability, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

    Weltraumforschung und Planetologie, Physikalisches Institut, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

20. N. Billot

    University of Geneva

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    Observatoire astronomique de l’Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

21. F. Biondi

    Max Planck Institute for Extraterrestrial Physics · Osservatorio Astronomico di Padova

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    INAF, Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy

    Max Planck Institute for Extraterrestrial Physics, Gießenbachstraße, 85748 Garching, Germany

22. A. Brandeker

    Stockholm University · AlbaNova

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    Department of Astronomy, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden

23. Christopher H. Broeg

    University of Bern · Center for Space and Habitability

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    Center for Space and Habitability, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

    Weltraumforschung und Planetologie, Physikalisches Institut, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

24. M.-D. Busch

    University of Bern

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    Physikalisches Institut, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

25. Andrew Collier Cameron

    University of St Andrews

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    Centre for Exoplanet Science, SUPA School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS, UK

26. Alexandre C. M. Correia

    Centro de Física da Universidade de Coimbra · University of Coimbra

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    CFisUC, Departamento de Física, Universidade de Coimbra, 3004516 Coimbra, Portugal

27. Sz. Csizmadia

    Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

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    Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489 Berlin, Germany

28. Patricio E. Cubillos

    Austrian Academy of Sciences · Space Research Institute · Osservatorio Astrofisico di Torino

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    INAF, Osservatorio Astrofisico di Torino, Via Osservatorio, 20, 10025 Pino Torinese To, Italy

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29. M. B. Davies

    Lund University

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    Centre for Mathematical Sciences, Lund University, Box 118, 221 00 Lund, Sweden

30. M. Deleuil

    Centre National de la Recherche Scientifique · Aix-Marseille Université

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    Aix Marseille Univ., CNRS, CNES, LAM, 38 rue Frédéric Joliot-Curie, 13388 Marseille, France

31. A. Deline

    University of Geneva

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    Observatoire astronomique de l’Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

32. L. Delrez

    University of Liège · KU Leuven

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    Astrobiology Research Unit, Université de Liège, Allée du 6 Août 19C, 4000 Liège, Belgium

    Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium

    Space sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Août 19C, 4000 Liège, Belgium

33. Olivier D S Demangeon

    Universidade do Porto · Institute of Astrophysics and Space Sciences · Centro de Astrofísica da Universidade do Porto

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    Departamento de Fisica e Astronomia, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal

    Instituto de Astrofisica e Ciencias do Espaco, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal

34. Brice-Olivier Demory

    University of Bern · Center for Space and Habitability

    Affiliation as printed

    Center for Space and Habitability, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

    Weltraumforschung und Planetologie, Physikalisches Institut, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

35. A. Derekas

    Eötvös Loránd University

    Affiliation as printed

    ELTE Gothard Astrophysical Observatory, 9700 Szombathely, Szent Imre h. u. 112, Hungary

36. B. Edwards Aachen SRON Netherlands Institute for Space Research

    Space Research Organisation Netherlands

    Affiliation as printed

    SRON Netherlands Institute for Space Research, Niels Bohrweg 4, 2333 CA Leiden, The Netherlands

37. David Ehrenreich

    University of Geneva

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    Centre Vie dans l’Univers, Faculté des sciences, Université de Genève, Quai Ernest-Ansermet 30, 1211 Genève 4, Switzerland

    Observatoire astronomique de l’Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

38. Anders Erikson

    Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

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    Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489 Berlin, Germany

39. L. Fossati

    Austrian Academy of Sciences · Space Research Institute

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    Space Research Institute, Austrian Academy of Sciences, Schmiedl-strasse 6, 8042 Graz, Austria

40. Malcolm C. Fridlund Aachen Leiden Observatory

    Leiden University · Leiden Observatory · Chalmers University of Technology

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    Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden

    Leiden Observatory, University of Leiden, PO Box 9513, 2300 RA Leiden, The Netherlands

41. D. Gandolfi

    University of Turin

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    Dipartimento di Fisica, Università degli Studi di Torino, via Pietro Giuria 1, 10125 Torino, Italy

42. K. Gazeas

    National and Kapodistrian University of Athens

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    National and Kapodistrian University of Athens, Department of Physics, University Campus, Zografos 157 84, Athens, Greece

43. M. Gillon

    University of Liège

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    Astrobiology Research Unit, Université de Liège, Allée du 6 Août 19C, 4000 Liège, Belgium

44. M. Güdel

    University of Vienna

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    Department of Astrophysics, University of Vienna, Türkenschanzs-trasse 17, 1180 Vienna, Austria

45. Maximilian N. Günther

    European Space Agency · European Space Research and Technology Centre

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    European Space Agency (ESA), European Space Research and Technology Centre (ESTEC), Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands

46. Ch. Helling

    Austrian Academy of Sciences · Graz University of Technology · Space Research Institute

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    Institute for Theoretical Physics and Computational Physics, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria

    Space Research Institute, Austrian Academy of Sciences, Schmiedl-strasse 6, 8042 Graz, Austria

47. K. G. Isaak

    European Space Agency · European Space Research and Technology Centre

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    European Space Agency (ESA), European Space Research and Technology Centre (ESTEC), Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands

48. F. Kerschbaum

    University of Vienna

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    Department of Astrophysics, University of Vienna, Türkenschanzs-trasse 17, 1180 Vienna, Austria

49. L. L. Kiss

    Eötvös Loránd University · Konkoly Observatory · HUN-REN Research Centre for Astronomy and Earth Sciences

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    ELTE Eötvös Loránd University, Institute of Physics, Pázmány Péter sétány 1/A, 1117 Budapest, Hungary

    Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, 1121 Budapest, Konkoly Thege Miklós út 15-17, Hungary

50. J. Korth

    Lund University

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    Lund Observatory, Division of Astrophysics, Department of Physics, Lund University, Box 118, 22100 Lund, Sweden

51. Kristine W. F. Lam

    Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

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    Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489 Berlin, Germany

52. J. Laskar

    Centre National de la Recherche Scientifique · Observatoire de Paris · Institut de Mécanique Céleste et de Calcul des Éphémérides

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    IMCCE, UMR8028 CNRS, Observatoire de Paris, PSL Univ., Sorbonne Univ., 77 av. Denfert-Rochereau, 75014 Paris, France

53. Alain Lecavelier des Etangs

    Centre National de la Recherche Scientifique · Institut d'Astrophysique de Paris · Université Pierre-et-Marie-Curie

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    Institut d’astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie, 98bis blvd. Arago, 75014 Paris, France

54. A. Leleu

    University of Geneva · University of Bern

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    Observatoire astronomique de l’Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

    Weltraumforschung und Planetologie, Physikalisches Institut, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

55. M. Lendl

    University of Geneva

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    Observatoire astronomique de l’Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

56. Demetrio Magrin

    Osservatorio Astronomico di Padova

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    INAF, Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy

57. Pierre F L Maxted

    Keele University

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    Astrophysics Group, Lennard Jones Building, Keele University, Staffordshire ST5 5BG, UK

58. Bruno Merín

    European Space Agency · European Space Astronomy Centre

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    European Space Agency, ESA – European Space Astronomy Centre, Camino Bajo del Castillo s/n, 28692 Villanueva de la Cañada, Madrid, Spain

59. C. Mordasini

    University of Bern · Center for Space and Habitability

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    Center for Space and Habitability, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

    Weltraumforschung und Planetologie, Physikalisches Institut, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

60. Göran Olofsson

    Stockholm University · AlbaNova

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    Department of Astronomy, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden

61. R. Ottensamer

    University of Vienna

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    Department of Astrophysics, University of Vienna, Türkenschanzs-trasse 17, 1180 Vienna, Austria

62. I. Pagano

    Osservatorio Astrofisico di Catania

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    INAF, Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania, Italy

63. E. Pallé

    Universidad de La Laguna · Instituto de Astrofísica de Canarias

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    Departamento de Astrofísica, Universidad de La Laguna, Astrofísico Francisco Sanchez s/n, 38206 La Laguna, Tenerife, Spain

    Instituto de Astrofísica de Canarias, Vía Láctea s/n, 38200 La Laguna, Tenerife, Spain

64. Gisbert Peter

    Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

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    Institute of Optical Sensor Systems, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489 Berlin, Germany

65. D. Pollacco

    University of Warwick

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    Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK

66. Didier P. Queloz

    University of Cambridge · ETH Zurich

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    Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK

    ETH Zurich, Department of Physics, Wolfgang-Pauli-Strasse 2, CH-8093 Zurich, Switzerland

67. Roberto Ragazzoni

    University of Padua · Osservatorio Astronomico di Padova

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    Dipartimento di Fisica e Astronomia “Galileo Galilei”, Università degli Studi di Padova, Vicolo dell’Osservatorio 3, 35122 Padova, Italy

    INAF, Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy

68. N. Rando

    European Space Agency · European Space Research and Technology Centre

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    European Space Agency (ESA), European Space Research and Technology Centre (ESTEC), Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands

69. Heike Rauer

    Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR) · Freie Universität Berlin

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    Institut fuer Geologische Wissenschaften, Freie Universitaet Berlin, Maltheserstrasse 74-100, 12249 Berlin, Germany

    Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489 Berlin, Germany

70. I. Ribas

    Institute of Space Sciences · Institut d'Estudis Espacials de Catalunya

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    Institut de Ciencies de l’Espai (ICE, CSIC), Campus UAB, Can Magrans s/n, 08193 Bellaterra, Spain

    Institut d’Estudis Espacials de Catalunya (IEEC), 08860 Castellde-fels (Barcelona), Spain

71. Nuno C. Santos

    Universidade do Porto · Institute of Astrophysics and Space Sciences · Centro de Astrofísica da Universidade do Porto

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    Departamento de Fisica e Astronomia, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal

    Instituto de Astrofisica e Ciencias do Espaco, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal

72. G. Scandariato

    Osservatorio Astrofisico di Catania

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    INAF, Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania, Italy

73. Damien Ségransan

    University of Geneva

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    Observatoire astronomique de l’Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

74. Attila E. Simon

    University of Bern · Center for Space and Habitability

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    Center for Space and Habitability, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

    Weltraumforschung und Planetologie, Physikalisches Institut, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

75. Alexis M. S. Smith

    Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

    Affiliation as printed

    Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489 Berlin, Germany

76. M. Stalport

    University of Liège

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    Astrobiology Research Unit, Université de Liège, Allée du 6 Août 19C, 4000 Liège, Belgium

    Space sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Août 19C, 4000 Liège, Belgium

77. S. Sulis

    Centre National de la Recherche Scientifique · Aix-Marseille Université

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    Aix Marseille Univ., CNRS, CNES, LAM, 38 rue Frédéric Joliot-Curie, 13388 Marseille, France

78. M. Gy. Szabó

    Eötvös Loránd University

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    ELTE Gothard Astrophysical Observatory, 9700 Szombathely, Szent Imre h. u. 112, Hungary

    HUN-REN-ELTE Exoplanet Research Group, Szent Imre h. u. 112., Szombathely 9700, Hungary

79. S. Udry

    University of Geneva

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    Observatoire astronomique de l’Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

80. B. Ulmer

    Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

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    Institute of Optical Sensor Systems, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489 Berlin, Germany

81. V. Van Grootel

    University of Liège

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    Space sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Août 19C, 4000 Liège, Belgium

82. J. Venturini

    University of Geneva

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83. E. Villaver

    Universidad de La Laguna · Instituto de Astrofísica de Canarias

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    Departamento de Astrofísica, Universidad de La Laguna, Astrofísico Francisco Sanchez s/n, 38206 La Laguna, Tenerife, Spain

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84. Nicholas A. Walton

    University of Cambridge

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    Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK